Demelza was surprised by the offer. Honestly, it surprised her more she clarified it as "not a date". So she was gay. Or bi at least. There'd been a few giveaways, but Demelza would never judge someone on what could be slips of the tongue. She was proud enough of her sexuality - both physically and who she was attracted to - to not have to filter through the words.
She shook her head. Smiling regretfully and genuinely, she said, "Sorry, but I can't. I have stuff to do." Night shift at Indulgences before a faction outing. "But another time? You know my name, just owl me." It was clear she meant for Katie to owl her. "We'll set something up. You never know how useful I can be." She smiled brightly.